Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Platefire on June 09, 2012, 04:14:13 pm
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Hopefully this will be last post on my Boogie for a while and I will be done soon. New reverb working and standby switch issues corrected.
While inside the amp I noticed some ugly looking- what appears to be corrosion on the board connections to power tube sockets. I would guess this was cause by heat? The amp is working fine at this point so I might just leave well enough alone! Attached pix is what I'm talking about. Is this something I should be concerned about? Platefire
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heat is the enemy. never use a PCB for power tubes...shame on MESA! clean off the excess rosin first, then re-flow joints.
--DL
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To be honest, I'm plum sceered of messing with that board. Not much experiance with PCB's. Did you see that board is partually mounted under the main board. When it comes to PCB's, got more questions than answers---
So the rosin you refered to is from the solder(rosin Solder)?
What would you clean it with and not destroy anything?
When you say re-flow joints---do you me re-melt the existing solder without adding any additional?
So in re-flowing the joints, would you do it directly to the exposed joints with the board in place as is?
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Don't fix what ain't broke!
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What would you clean it with and not destroy anything?
http://www.mgchemicals.com/products/fluxrem.html (http://www.mgchemicals.com/products/fluxrem.html)
So the rosin you refered to is from the solder(rosin Solder)?
yes, sometime it is added to help the solder bond.
When you say re-flow joints---do you me re-melt the existing solder without adding any additional?
remove old solder then re-flow with new solder.
remove old solder with solder wick or solder puller.
http://www.wassco.com/Products/Edsyn-Deluxe-Soldapullt-Solder-Puller__EDY-DS017.aspx (http://www.wassco.com/Products/Edsyn-Deluxe-Soldapullt-Solder-Puller__EDY-DS017.aspx)
--DL
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Thanks DL!
Nothing like having the right tools---and experiance in which I'm lacking in that area. Since I'm such a good procrastinator, that looks like something I could procrastinate real good on! But I appreciate the Links you provided---now I know what to use if I decide to dive in.
My inclination is this, continue to use it until it fails or become problematic, then do what you said and if some how I mess it up un-usable, then pull the little board and install real sockets in the chassis. I don't know if that is stinking thinking but that is exactly what I'm thinking! Thanks, Platefire
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Ah, the joys of pcb amp repair.
The corrosion is normal. You'll see it on many pcb amps sooner or later, some worse than others. It's on every boogie I've worked on.
In general there isn't anything to worry about until a component fails and you have to replace it. Then you have to be very careful with the pcb. On some older pcb's that have seen a lot of heat the board material can become brittle and the eyelets can come off/out easily. Solder wick, vacuum pumps, hakko desoldering guns/stations, I've used them all and I've found that they all have their place.
Solder wick has become my new friend. A little extra flux on the pcb makes the solder wick suck up solder MUCH quicker/more thoroughly.
The eyelets do come out sometimes, especially on old, well weathered boards. If it has to be "jumpered" then it has to. I don't like doing it but some of the amps I've repaired have been to hell and back. A lot of amp repair customers don't have a lot of money to drop on their gear. They just want it fixed. All the complaints I've read from other techs concerning the repair of cheap pcb amps are valid in my opinion.
I never have any time to build amps because I'm always doing fun (sarcasm) stuff like repairing pcb amps.
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Well I missed a lot of potential repair work because I am brutally honest with people that call. I put up posters several years ago in a lot of local music stores that I build and repair old style point to point amps but most of the people that call are looking for help on SS amps of Hybred amps. I tell them that I haven't had experiance with those type amps and it would be better take it to an experanced tech but if they can't find anybody, I would take a look and see what I can do--which is the truth---but not what they really want to hear! So far none has ever called me back. I have repaired serveral old style fenders and Marshalls. I've been tempted to tell the SS & Hybred people to bring it on, and then try to figure it out after I've got it in hand--but I can't do that. Plate
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Just bought a new roll of 60/40 from radio shack. Platefire
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Yup, my RS has the 63/37 which works fine too.
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Of course there isn't any telling how old my local radio shack stock is. Sometimes I think I'm one of the only ones buying solder gear or small electronic items locally because I find they are not restocking a lot of that stuff. They are also dealers in cell phone and TV sat services. When I'm in there that's the trust of the activities and focus. I guess they are going where the money is.
Thank the Lord for internet parts like Doug and others that we can get what we need! Platefire
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Thank the Lord for internet parts like Doug and others that we can get what we need!
Very true! Plus, when I go to checkout here, there is no "batteries sir? Got a special on batteries today" and "how about a FREE $15 gift card for letting us scan your cel phone?". I always politely decline, but in my head I'm screaming at him to just STFU and take my money. :laugh: